Process death
Android killing a background app to free memory, then recreating the last screen from saved state when the user returns.
Definition
No callback runs before the process is killed. When the user comes back from Recents, Android recreates the Activity and restores saved-instance state (SavedStateHandle, rememberSaveable, the navigation back stack), but ViewModels, singletons and in-memory caches start empty. Screens must be rebuildable from saved ids and persisted data.
In practice
A checkout keeps the cart id in SavedStateHandle and reloads the cart after the user returns from their banking app.